Adapter for three conductor electrical power distribution track

ABSTRACT

An adapter for electrically and mechanically securing an electrical fixture to an elongated three conductor, two circuit electrical power distribution track of the type having an open mouthed channel running for its length with two of the conductors disposed on opposite sides of the channel and the third conductor disposed at a transverse inwardly and upwardly displaced location therefrom. The adapter is of the type which has a cylindrical body adapted at one end for securance to an electrical light fixture and having a connecting head at its opposite end for securing the adapter to the channel upon insertion of the head into the channel and rotation through 90*. The head is provided with a pair of contact fingers in electrically conducting relation to an electrical lead-in arrangement for the fixture, which fingers are also arranged to engage either of two circuit pairs of the three conductors upon insertion and rotation of the head in the channel. The principal feature of the adapter is that one of the contact fingers is removably insertable into the head at two positions transversely and longitudinally displaced from each other and in each position the finger is in electrically conducting relation to the electrical lead-in arrangement for the fixture. In one position, the removable contact finger is engageable with one of the side conductors of the channel while the fixed finger is engageable with the opposite second side conductor. In the other position, the removable finger is engageable with the second side conductor. In this manner, a single adapter may be employed to selectively connect a fixture to either of the two circuits of the three conductor power distribution system.

United States Patent 1' Contratto 1 June 5,1973

[54] ADAPTER FORTHREE CONDUCTOR ELECTRICAL POWER DISTRIBUTION TRACK [75] Inventor: James Contratto, San Leandro,

Calif.

[73] Assignee: U.S. Industries, Inc., New York,

[22] Filed: Sept. 20, 1971 [21] Appl. No.: 181,973

[52] 0.8. CI. ..339/21 R [51] Int. Cl. .J-lOlr 9/00 [58] Field of Search... .;....339/l4,.20-24 [56] References Cited UNITED STATES PATENTS 3,496,518 2/1970 Neumann et al ..339/21 R 3,503,032 3/1970 Routh et al. ..339/l4 R 3,613,045 10/1971 Routh et al. ..339/21 R 3,559,146 1/1971 Valtonen ..339/21 S Primary Examiner-Marvin A. Champion Assistant Examiner-Robert A. Hafer Att0rneyJoseph B. Gardner [57] ABSTRACT An adapter for electrically and mechanically securing an electrical fixture to an elongated three conductor,

two circuit electrical power distribution track of the type having an open mouthed channel running for its length with two of the conductors disposed on opposite sides of the channel and the third conductor disposed at a transverse inwardly and upwardly displaced location therefrom. The adapter is of the type which has a cylindrical body adapted at one end for securance to an electrical light fixture and having a connecting head at its opposite end for securing the adapter to the channel upon insertion of the head into the channel and rotation through 90. The head is provided with a pair of contact fingers in electrically conducting relation to an electrical lead-in arrangement for the fixture, which fingers are also arranged to engage either of two circuit pairs of the three conductors upon insertion and rotation of the head in the channel. The principal feature of the adapter is that one of the contact fingers is removably insertable into the head at two positions transversely and longitudinally displaced from each other and in each position the finger is in electrically conducting relation to the electrical lead-in arrangement for the fixture. In one position, the removable contact finger is engageable with one of the side conductors of the channel while the fixed finger is engageable with the opposite second side conductor. 1n the other position, the removable finger is engageable with the second side conductor. In this manner, a single adapter may be employed to selectively connect a fixture to either of the two circuits of the three conductor power distribution system.

9 Claims, 4 Drawing Figures 52. a i 4 a;

J. nix

Patented June 5, 1973 0 5 mm m m2 v\ E mm 6 A mm. M

ADAPTER FOR THREE CONDUCTOR ELECTRICAL POWER DISTRIBUTION TRACK BACKGROUND OF THE INVENTION Heretofore, various electrical power distribution systems of the type which permit selective positioning of electrical fixtures such as lamps at various locations along a track defined by a channel having therealong three electrically isolated conductors providing two electrical power distribution circuits. In addition, quick release lockable adapters have been provided to mechanically and electrically secure the fixtures to the track channel at the desired locations. For purposes of power balance between the two circuits of the distribution system it is desirable that some of the fixtures be electrically connected to one pair of circuit-defining conductors forming a first power circuit and other of the fixtures be electrically connected to a second pair of circuit-defining conductors forming the second power circuit.

To these ends it has heretofore been necessary either to provide two different types of adapters: namely, one type arranged to connect a fixture to the conductors of the first circuit, and a second type arranged to connect a fixture to the conductors of the second circuit; or to provide a roller complex adapter having multiple contacts and selector means operative to permit the contacts to be manipulated into selective engagement with the appropriate conductors. As respects adapter cooperation with the distribution track, the channel thereof has typically been open mouthed along its entire length with two conductors respectively disposed on opposite sides thereof and a third conductor disposed inwardly of the others and upwardly therefrom, the conductors being mounted within an insulator that separates the conductors from each other and from the channel which is usually metal. The prior adapters include a connecting head equipped with opposed outwardly extending cars which are positionally polarized as by being offset relative to each other along the longitudinal axis of the head. Upon insertion of the head into the open mouth of the channel and rotation of the head through 90 to engage the ears within correspondingly offset slots in the sides .of the channel (or comparable arrangement to engage the ears and channel), the adapter is mechanically supported by the channel and depends therefrom. In one type of adapter, a pair of contact fingers fixedly secured to the head thereof extend therefrom and upon such angular displacement of the adapter are forced into electrical connection with a pair of the channel conductors so as to establish an electrical connection of a fixture therewith. Such contact fingers project radially outwardly from the head on opposite sides thereof and electrically connect a fixture to the previously noted first circuit of the power distribution system. A second type of adapter is similarly provided with a fixed pair of contact fingers except that one finger is inwardly and upwardly offset from the position occupied by the counterpart finger in the first type of adapter. Upon insertion of the adapter head into the channel and rotation of the adapter through 90, the contact fingers thereof thus engage one side conductor and the inwardly and upwardly displaced conductor of the channel to thereby connect a fixture to the previously noted second circuit of the power distribution system.

In a multiple-contact, selector-equipped adapter, the particular conductor pairs with which the contacts are connected is determined by manual manipulation of the selector mechanism. In any case, however, it is desirable from the standpoint of simplicity, interchangeability, versatility, and economy of manufacture, that a single simplified adapter be provided for selectively connecting a fixture to either of the two circuits of the power distribution system.

SUMMARY OF THE INVENTION The present invention relates to an improved adapter for mechanically and electrically connecting a light fixture to a three-conductor, two-circuit, track-type electrical power distribution system, and it is more particularly directed to an adapter which is arranged for selective electrical connection to either of the two circuits of the distribution system.

It is an object of the invention to provide an adapter arranged at one end for connection to a light fixture and having a connecting head at its opposite end for re- Ieasable locking engagement with a track channel of a three-conductor, two-circuit electrical power distribution system, the head having a pair of contact fingers for electrically contacting a pair of the channel conductors upon mechanical engagement of the adapter with the channel, one of the contact fingers being selectively positionable for electric engagement with either of two channel conductors that provide the two circuits of the distribution system in common with the third conductor.

Another object of the invention is in the provision of an adapter of the class described having a locking head equipped with a fixed contact finger in electrical connection with one lead wire of a fixture associated with the adapter and which finger is engageable with one side conductor of the track channel; and further equipped with a removable contact finger for selectively contacting the other side conductor of the channel or the inwardly and upwardly displaced conductor thereof, such selectively positionable conductor being insertable through either of two correspondingly positioned passages of the head into electrically conducting relation with the second lead wire of the fixture associated with the adapter.

A further object of the invention is to provide an adapter of the type set forth having an internal electrical contact or spring terminal electrically connected with the second lead wire of an associated fixture and operative automatically to establish an electrical connection with the movable contact irrespective of which passage it is positioned within; such internal contact having a pair of spring loaded lugs projecting into the two passages for electrically conducting and mechanically grasping engagement with the removable contact finger upon insertion into either of the passages.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary perspective view of a power distribution track and a plurality of adapters in accordance with the present invention securing lighting fixtures thereto;

FIG. 2 is a longitudinal sectional view of an adapter in accordance with the present invention;

FIG. 3 is an exploded perspective view of the adapter depicting the movable contact finger thereof disposed so as to be placed in an alternative position to that shown in FIG. 2', and

FIG. 4 is an enlarged broken sectional view illustrating the movable contact and spring terminal in engagement therewith.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1 in detail, there is shown a power distribution track 11 of a type including an open mouthed channel 12 defined by a pair of parallel spaced side walls 13 and 14 interconnected at their upper ends by means of a web 16. The web is formed with an upwardly stepped central longitudinally extending portion 17 and is adapted for securance of hanger brackets 18 for securing the channel to a ceiling. Sidewalls 13 and 14 are respectively provided with transversely inwardly projecting rails 19 and 21 at their lower ends, such rails being in parallel spaced relation to the web 16 and being centrally transversely spacedapart so as to define an open mouth or slot therebetween at the underside of the channel. One rail 19 is formed with an upwardly extending lip 22 longitudinally thereof. Within the channel there is provided a conformed insulating member 23 which carries a pair of conductors 24 and 26 respectively adjacent the intersections of the sidewalls l3 and 14 with the web 16 of the channel. The insulating member 23 carries a third conductor 27 adjacent one corner of the upwardly extending portion 17 of web 16, whereby the third conductor 27 is transversely inwardly and upwardly displaced from the two opposed side conductors 24 and 26. It is of importance to note that as thus arranged the pair of side conductors 24 and 26 provide one circuit of the electrical power distribution system, while the upper conductor 27 and side conductor 24 provide the second circuit of the system.

A plurality of adapters 28, in accordance with the present invention, are mechanically and electrically secured to the power distribution track channel 12 at longitudinally spaced positions therealong to facilitate mechanical support of electrical fixtures such as lamps 29 from the channel as well as electrical connection of the fixtures to the electrical circuits of the distribution track system. In basic respects the adapters 28 are generally conventional in that they include a hollow cylindrical body 31 adapted at one end for securance to a lamp 29, or other fixture, and having a locking head 32 at its opposite end adapted for mechanical and electrical securing engagement with the channel 12. More particularly, the lower end of the body 31 is formed with an end closure wall 33 and a toggle switch 34 is mounted within the body and secured to the closure wall 33, as by means of screws 36. The switch has an actuating on-off lever 37 which projects through the peripheral wall of the body 31, and a threaded support sleeve 38 which depends through closure wall 33 is traversed by a pair of wire leads 39 and 41 for electrical connection to a lamp 29 mechanically secured to the stem. The switch further includes a pair of lead-in conductors 42 and 43 which comprise the electrical lead-in arrangement for the fixture.

As regards the head 32, same will be seen to include a cylindrical plug 44 of insulating plastic material which is removably secured within an open upper end of the body 31, as by means of set screws 46. The plug has a generally dome-shaped upper end including an inwardly stepped cylindrical portion 47 which upwardly terminates in'a second inwardly stepped cylindrical portion 48, in turn upwardly terminating in a third inwardly stepped cylindrical portion 49. The cylindrical portion 47 has a pair of opposed outwardly radially extending ears 51 and 52 which are offset relative to each other longitudinally of the head. With the head oriented such that the ears are aligned with the bottom longitudinal opening of the track channel 12 the head may be inserted thereinto at any desired longitudinal position. Then upon rotation of the adapter through 90, ears 51 and 52 respectively engage the lip 22 and the interior surface of rail 21 to mechanically support the adapter from the channel.

The head is also provided with an abutment stop or projection 53 outwardly adjacent the cylindrical portion 47 at a position circumferentially spaced 90 from ears 51 and S2. The projection is spring loaded upwardly, and it is equipped with a tab 54 extending outwardly through the peripheral wall of the body 31 to enable the projection to be depressed by a user. The projection serves as a stop or abutment operative to engage the facing longitudinal edges of channel rails 19 1. and 21 upon rotation of the adapter head into the operative position shown in FIG. 1 to prevent further rotation thereof to thereby lock the adapter in operative position. Removal of the adapter is permitted by displacing the tab 54 downwardly to depress the projection 53 and thereby withdraw it from between the rails 19 and 20. The adapter 28 can then be rotated to align the ears 51 and 52 with the channel opening and enable the head to be withdrawn. The head is also provided with a pair of contact fingers 56 and 57 for electrically contacting two of the three channel conductors 24, 26, 27 when the head is locked in operative position within the channel, which fingers serve to conduct electricity from the channel conductors to the fixture lead-in conductors 42 and 43.

To the extent thus far described, the adapter 28 is disclosed in Routh and Contratto US. Pat. No. 3,503,032, and reference may be made thereto for further details concerning the same. However, such prior adapter has had fixed contact fingers 56 and 57 appropriately positioned either to engage channel conductors 24 and 26 and thereby connect the fixture 29 to the first circuit of the power distribution system or to engage the channel conductors 26 and 27 and thereby connect the fixture. to the second circuit of the power distribution system. As previously stated, this has required two difierent adapters each with fixed contacts.

In accordance with the particularly salient aspects of the present invention, the foregoing disadvantage is overcome by arranging adapter 28 such that its contact fingers 56 and 57 may be selectively and conveniently made to engage either channel conductors 24 and 26 or channel conductors 26 and 27. In this regard, contact finger 56 is mounted in fixed position in the head plug 44 at a location to engage channel conductor 24 when the head is locked in position in the channel, and suchfinger is electrically connected to fixture lead-in conductor 42. l-Iowever, contact finger 57 is selectively interchangeably mountable in the head plug at either of two positions. In the first position, the finger engages channel conductor 26 upon locking of the adapter head in the channel, while in the second position the contact finger engages channel conductor 27. Provision is made for electrical connection of contact finger S7 to fixture lead-in conductor 43 in either contact finger position.

Considering now the contact finger arrangement in more detail, it is to be noted that finger 56 projects right-angularly from an elongated shank 58 which is longitudinally secured within head plug 44. More particularly, the shank extends into the plug at the intersection of cylindrical portions 47 and 48 such that finger 56 projects radially outward from such intersection. Shank 58 extends longitudinally inwardly into a recess 59 provided in the base of the plug in communication with the interior of the body 31, whereat the lower end of the shank is secured to lead-in conductor 42. A passage 61 extends longitudinally through the plug from the intersection of cylindrical portions 48 and 49 to recess 59, and cylindrical portion 48 includes a notch 62 at the upper end of the passage which extends downwardly to the intersection between cylindrical portions 47 and 48 at a point diametrically opposed to finger 56.

In addition, the plug includes a second longitudinal passage 63 which extends centrally therethrough from the upper end of cylindrical portion 49 to the recess 59. The upper end of such cylindrical portion is formed with a groove 64 that extends radially outward from passage 63 and is aligned with the notch 62. A partitioning wall 66 depends from the plug into the recess 59 in interposition to the terminations of passages 61 and 63 in the recess. A generally hairpin shaped electrical contact 67 is secured to wall 66 to extend about its lower end and along the opposite sides thereof. The upper ends of the contact are outwardly turned to define resilient lugs 68 and 69 respectively extending across the terminations of passages 61 and 63. Such contact 67 is electrically connected to lead-in conductor 43. Contact finger 57 projects right-angularly outward from an elongated shank 71 which is removably insertable into either of the passages 61 or 63. Thus, upon full insertion of the shank into passage 61 the finger 57 engages the lower end of notch 62 such that the finger projects radially outward from the intersection of cylindrical portions 47 and 48 of the head plug at a point diametrically opposed to finger 56. The lower end of the shank engages resilient lug 68 to thereby be in electrical connection with lead-in conductor 43. In addition, the lug resiliently retains the finger and shank in position. It will be thus appreciated that when the head is locked in position in the channel, contact fingers 56 and 57 engage the opposed channel side conductors 24 and 26 and connect fixture 29 to the first circuit of the power distribution system.

In the event it is desired to connect fixture 29 to the second circuit of the power distribution system, the finger 57 and shank 71 are withdrawn from passage 61 and the shank is fully inserted into passage 63 to engage the finger in groove 64. The finger is thus now in an upwardly and inwardly displaced position such that when the head is locked in position in the channel, the fingers 56 and 57 will respectively engage side conductor 24 and the inwardly and upwardly disposed conductor 27. The shank 71 engages resilient lug 69 so as to provide electrical connection with lead-in conductor 43, and the lug resiliently retainsthe shank in the passage to secure the finger in position. The fixture 29 is thus now connected to the second circuit of the power distribution system.

The head 32 is of multipartite construction and, in the form shown, comprises three components respectively defined by the plug 44, the partitioning wall structure 66, and the central component constituting the-integral second and third stepped cylindrical sections 48 and 49. These elements of the head are formed of a dialectric material affording adequate electrical insulation between the contacts 56 and 57, and various materials may be used for this purpose including synthetic plastic materials such as polyvinylchloride. The cylindrical plug 44 extends downwardly into the body 31 and is secured thereto by the set screws 46, as previously explained, and the plug has a large central opening or passage extending axially therethrough and into which portions of both the partitioning wall structure 66 and stepped component 48,49 extend.

In this reference, the central passage through the plug 44 is substantially square-shaped in cross section, and the wall structure 66 is in the form of a hollow, generally square-shaped sleeve that fits into the passage and snugly engages the same with a relatively tight friction fit on opposite sides thereof, and is spaced slightly from the sidewalls of the plug on its opposite two sides to form therewith passages for .the contacts 56 and 57, as is most evident in FIG. 4. The hollow interior 72 of the wall structure 66 is also generally square-shaped in cross section, and seated therewithin is the downwardly projecting nose 73 of the stepped component 48,49. The nose 73 frictionally engages the circumjacent surfaces of the wall structure 66, and at least a portion (the stepped section 48) of the component 48,49 overlies the contact 56 so as to constrain the same within the passage therefor defined between the plug 44 and partition wall structure 66. As previously explained, the notch 62 in the stepped section 48 enables the contact 57 to be removed for replacement in the central passage 63. Such tripartite construction of the head 32 is advantageous in that it simplifies and facilitates assembly including location of the contact 56 within the passage therefor, and at the same time it enables the contact 57 to be selectively positioned within either of the passages 61 or 63 while holding the same firmly in either such passage in cooperation with the resilient terminal 67. A grounding strap 74 extends upwardly through an opening or passage provided therefor in the plug 44 in underlying relation with the lip 51 so as to frictionally engage the track channel 11 and thereby establish an electric connection therewith, the track channel being metal. The strap 74 is also connected electrically via one of the set screws 46 to the metal body 31 which may in turn be connected through a conductor (not shown) to the associated fixture 29. Accordingly, the casing of the fixture is thereby grounded through. casing or body 31,-set screw 46, and strap 74 to the track channel 11, all as previously explained in the aforementioned US Pat. No. 3,503,032.

While in the foregoing specification an embodiment of the invention has been set forth in considerable 'detail for purposes of making a complete disclosure thereof, it will be apparent to those skilled in the art that numerous changesmay be made in such details without departing from the spirit and principles of the invention.

What is claimed is:

1. An adapter for electrically and mechanically securing an electrical fixture to an elongated electrical power distribution track of the type having an open mouthed channel running for its length with first and second conductors extending longitudinally along the opposite interior sidewalls of the channel and a third conductor extending longitudinally of said channel at a position inwardly and upwardly displaced from said first and second conductors, said conductors being mutually insulated with the first and second conductors providing a first power distribution circuit and the first and third conductors providing a second power distribution circuit, said adapter comprising a body adapted at one end for securance to an electrical fixture and having a connecting head at its opposite end for securance to said channel, a fixture lead-in arrangement disposed in said body including first and second lead-in conductors, a first contact finger mounted in fixed position in said head for contacting engagement with said first channel conductor upon securance of said head to said channel and being electrically connected to said first lead-in conductor, a second contact finger carried by said head and being selectively positionable between first and second transversely and longitudinally spaced positions, said second contact finger in said first position thereof being contactingly engageable with said second channel conductor, said second contact finger in said second position thereof being contactingly engageable with said third channel conductor, and means carried within said body for electrically connecting said second contact finger to said second lead-in conductor in either of said first and second positions, said second contact finger having an elongated shank extending right-angularly therefrom, said shank being longitudinally removably insertable into said head through first and second transversely spaced passages provided by said head and having longitudinally spaced exterior openings to thereby dispose said contact finger in either of said first and second positions.

2. An adapter according to claim 1, further defined by the electrical connecting means comprising an electrical contact carried by said head within said body and having a pair of resilient lugs projecting into intersection with said first and second passages for engagement with said shank of said second contact finger, said contact being electrically connected to said second lead-in conductor.

3. An adapter according to claim 1, further defined by said head being of insulating material and having a generally dome-shaped configuration, said head having a first inwardly stepped cylindrical portion terminating upwardly in a second inwardly stepped cylindrical portion, said second portion terminating upwardly in a third inwardly stepped cylindrical portion, and a pair of opposed ears projecting radially outward from said first cylindrical portion for securing engagement with opposed rails of said channel, said first contact finger projecting radially outward from the intersection of said first and second cylindrical portions, said first passage extending longitudinally through said head from the intersection of said second and third cylindrical portions at a point diametrically opposed to said second contact fingers, said second cylindrical portion having a notch at the exterior end of said first passage extending downwardly to the intersection of said first and second cylindrical portions for receiving said second contact finger upon full insertion of said shank into said first passage, said second passage extending longitudinally centrally through said head from the upper end of said third cylindrical portion, said upper end of said third cylindrical portion having a groove extending radially outward from said second passage in alignment with said notch for receiving said second contact finger upon full insertion of said shank into said second passage.

4. An adapter according to claim 3, further defined by the electrical connecting means comprising an electrical contact carried by said head within said body and having a pair of resilient lugs projecting into intersection with said first and second passages for retentive engagement with said shank, said contact being electrically connected to said second lead-in conductor.

5. An adapter according to claim 3, further defined by said head having a recess in its base in communication with the interior of said body, said first and second passage terminating in said recess, said head having a partitioning wall depending into said recess in interposition to the terminationsof said first and second passages, said contact having a generally hairpin shaped configuration and extending about the lower end and along the opposite sides of said wall, said lugs oppositely projecting from the upper ends of said contact and extending across the terminations of said first and second passages.

6. An adapter for electrically and mechanically securing an electrical fixture to an elongated electrical power distribution track of the type having an open mouthed channel running for its length with first and second conductors extending longitudinally along the opposite interior sidewalls of the channel and a third conductor extending longitudinally of said channel at a position inwardly and upwardly displaced from said first and second conductors, said conductors being mutually insulated with the first and second conductors providing a first power distribution circuit and the first and third conductors providing a second power distribution circuit, said adapter comprising a body adapted at one end for securance to an electrical fixture and having a connecting head at its opposite end for securance to said channel, a fixture lead-in arrangement disposed in said body including first and second lead-in conductors, a first contact finger mounted in fixed position in said head for contacting engagement with said first channel conductor upon securance of said head to said channel and being electrically connected to said first lead-in conductor, a second contact finger carried by said head and being selectively positionable between first and second transversely and longitudinally spaced positions, said second contact finger in said first position thereof being contactingly engageable with said second channel conductor, said second contact finger in said second position thereof being contactingly engageable with said third channel conductor, and means carried within said body for electrically connecting said second contact finger to said second lead-in conductor in either of said first and second positions, said head including a plurality of interrelated components one of which is a plug carried by said body and being provided with a central opening therethrough, another is a partition wall structure disposed within said central opening and defining passages with said plug for said contacts and defining an axially disposed opening therethrough, and still another being a stepped component having a nose extending into said axial opening and defining an axially disposed passage adapted to removably receive therein the aforesaid second contact finger.

7. An adapter according to claim 6 further defined by the electrical connecting means comprising an electrical contact carried by said wall structure within said body and having a pair of resilient lugs projecting into intersection with said first and second passages for selective engagement with the shank of said second contact finger, said contact being electrically connected to said second lead-in conductor.

8. An adapter for electrically and mechanically securing an electrical fixture to an elongated electrical power distribution track of the type having an open mouthed channel running for its length with first and second conductors extending longitudinally along the opposite interior sidewalls of the channel and a third conductor extending longitudinally of said channel at a position transversely and longitudinally displaced from said second conductor, said conductors being mutually insulated with the first and second conductors providing a first power distribution circuit and the first and third conductors providing a second power distribution circuit, said adapter comprising a body adapted for securance to an electrical fixture and having a connecting head for securance to said channel, a fixture lead-in arrangement including first and second lead-in conductors, a first contact mounted in fixed position in said head for contacting engagement with said first channel conductor upon securance of said head to said channel and being electrically connected with said first lead-in conductor, a second contact having an elongated shank and being carried by said head and selectively positionable with respect thereto between first and second transversely and longitudinally spaced positions, said contact in said first position thereof being contactingly engageable with said second channel conductor and in said second position thereof being contactingly engageable with said third channel conductor, and means carried within said body for electrically connecting said second contact to said second lead-in conductor in either of said first and second positions, said head having a pair of transversely spaced longitudinally extending passages terminating at longitudinally spaced locations and respectively defining said first and second positions, said shank being selectively insertable into said passages to establish the first and second positions of said second contact.

9. An adapter according to claim 8 in which said electrical connecting means comprises an electrical contact carried by said head within said body and projecting into intersection with each of said passages for engagement with said second contact upon insertion of said shank thereof into either of said passages. 

1. An adapter for electrically and mechanically securing an electrical fixture to an elongated electrical power distribution track of the type having an open mouthed channel running for its length with first and second conductors extending longitudinally along the opposite interior sidewalls of the channel and a third conductor extending longitudinally of said channel at a position inwardly and upwardly displaced from said first and second conductors, said conductors being mutually insulated with the first and second conductors providing a first power distribution circuit and the first and third conductors providing a second power distribution circuit, said adapter comprising a body adapted at one end for securance to an electrical fixture and having a connecting head at its opposite end for securance to said channel, a fixture lead-in arrangement disposed in said body including first and second lead-in conductors, a first contact finger mounted in fixed position in said head for contacting engagement with said first channel conductor upon securance of said head to said channel and being electrically connected to said first lead-in conductor, a second contact finger carried by said head and being selectively positionable between first and second transversely and longitudinally spaced positions, said second contact finger in said first position thereof being contactingly engageable with saId second channel conductor, said second contact finger in said second position thereof being contactingly engageable with said third channel conductor, and means carried within said body for electrically connecting said second contact finger to said second lead-in conductor in either of said first and second positions, said second contact finger having an elongated shank extending right-angularly therefrom, said shank being longitudinally removably insertable into said head through first and second transversely spaced passages provided by said head and having longitudinally spaced exterior openings to thereby dispose said contact finger in either of said first and second positions.
 2. An adapter according to claim 1, further defined by the electrical connecting means comprising an electrical contact carried by said head within said body and having a pair of resilient lugs projecting into intersection with said first and second passages for engagement with said shank of said second contact finger, said contact being electrically connected to said second lead-in conductor.
 3. An adapter according to claim 1, further defined by said head being of insulating material and having a generally dome-shaped configuration, said head having a first inwardly stepped cylindrical portion terminating upwardly in a second inwardly stepped cylindrical portion, said second portion terminating upwardly in a third inwardly stepped cylindrical portion, and a pair of opposed ears projecting radially outward from said first cylindrical portion for securing engagement with opposed rails of said channel, said first contact finger projecting radially outward from the intersection of said first and second cylindrical portions, said first passage extending longitudinally through said head from the intersection of said second and third cylindrical portions at a point diametrically opposed to said second contact fingers, said second cylindrical portion having a notch at the exterior end of said first passage extending downwardly to the intersection of said first and second cylindrical portions for receiving said second contact finger upon full insertion of said shank into said first passage, said second passage extending longitudinally centrally through said head from the upper end of said third cylindrical portion, said upper end of said third cylindrical portion having a groove extending radially outward from said second passage in alignment with said notch for receiving said second contact finger upon full insertion of said shank into said second passage.
 4. An adapter according to claim 3, further defined by the electrical connecting means comprising an electrical contact carried by said head within said body and having a pair of resilient lugs projecting into intersection with said first and second passages for retentive engagement with said shank, said contact being electrically connected to said second lead-in conductor.
 5. An adapter according to claim 3, further defined by said head having a recess in its base in communication with the interior of said body, said first and second passage terminating in said recess, said head having a partitioning wall depending into said recess in interposition to the terminations of said first and second passages, said contact having a generally hairpin shaped configuration and extending about the lower end and along the opposite sides of said wall, said lugs oppositely projecting from the upper ends of said contact and extending across the terminations of said first and second passages.
 6. An adapter for electrically and mechanically securing an electrical fixture to an elongated electrical power distribution track of the type having an open mouthed channel running for its length with first and second conductors extending longitudinally along the opposite interior sidewalls of the channel and a third conductor extending longitudinally of said channel at a position inwardly and upwardly displaced from said first and second conductors, said conducTors being mutually insulated with the first and second conductors providing a first power distribution circuit and the first and third conductors providing a second power distribution circuit, said adapter comprising a body adapted at one end for securance to an electrical fixture and having a connecting head at its opposite end for securance to said channel, a fixture lead-in arrangement disposed in said body including first and second lead-in conductors, a first contact finger mounted in fixed position in said head for contacting engagement with said first channel conductor upon securance of said head to said channel and being electrically connected to said first lead-in conductor, a second contact finger carried by said head and being selectively positionable between first and second transversely and longitudinally spaced positions, said second contact finger in said first position thereof being contactingly engageable with said second channel conductor, said second contact finger in said second position thereof being contactingly engageable with said third channel conductor, and means carried within said body for electrically connecting said second contact finger to said second lead-in conductor in either of said first and second positions, said head including a plurality of interrelated components one of which is a plug carried by said body and being provided with a central opening therethrough, another is a partition wall structure disposed within said central opening and defining passages with said plug for said contacts and defining an axially disposed opening therethrough, and still another being a stepped component having a nose extending into said axial opening and defining an axially disposed passage adapted to removably receive therein the aforesaid second contact finger.
 7. An adapter according to claim 6 further defined by the electrical connecting means comprising an electrical contact carried by said wall structure within said body and having a pair of resilient lugs projecting into intersection with said first and second passages for selective engagement with the shank of said second contact finger, said contact being electrically connected to said second lead-in conductor.
 8. An adapter for electrically and mechanically securing an electrical fixture to an elongated electrical power distribution track of the type having an open mouthed channel running for its length with first and second conductors extending longitudinally along the opposite interior sidewalls of the channel and a third conductor extending longitudinally of said channel at a position transversely and longitudinally displaced from said second conductor, said conductors being mutually insulated with the first and second conductors providing a first power distribution circuit and the first and third conductors providing a second power distribution circuit, said adapter comprising a body adapted for securance to an electrical fixture and having a connecting head for securance to said channel, a fixture lead-in arrangement including first and second lead-in conductors, a first contact mounted in fixed position in said head for contacting engagement with said first channel conductor upon securance of said head to said channel and being electrically connected with said first lead-in conductor, a second contact having an elongated shank and being carried by said head and selectively positionable with respect thereto between first and second transversely and longitudinally spaced positions, said contact in said first position thereof being contactingly engageable with said second channel conductor and in said second position thereof being contactingly engageable with said third channel conductor, and means carried within said body for electrically connecting said second contact to said second lead-in conductor in either of said first and second positions, said head having a pair of transversely spaced longitudinally extending passages terminating at longitudinally spaced locations and respectively Defining said first and second positions, said shank being selectively insertable into said passages to establish the first and second positions of said second contact.
 9. An adapter according to claim 8 in which said electrical connecting means comprises an electrical contact carried by said head within said body and projecting into intersection with each of said passages for engagement with said second contact upon insertion of said shank thereof into either of said passages. 